FR2713996A1 - Multiple pumping arrangement for multi-compartment tank used for vehicle fuel tanks - Google Patents

Abstract

The arrangement is used for a reservoir (1) with several compartments with a main compartment (2) and auxiliary compartment (3). Each compartment has a supply and return circuit (5,9) with a supply pipe (6,10) and return pipe (8,17). A control valve is arranged in each supply circuit for each auxiliary compartment. This opens when the level of liquid is greater than a limiting value. The valve is closed when the level of liquid in the auxiliary compartment is below the limiting value.

Description

 The present invention relates generally to tanks, in particular for motor vehicles, and more precisely to multiple draw devices in tanks comprising several compartments.

 The multiple drawing device according to the invention is of the type which comprises in each compartment a liquid suction pipe and a return pipe intended to convey the unconsumed liquid to each compartment, the suction pipes being arranged to suck the liquid simultaneously in all compartments where the quantity of liquid is sufficient.

 Multi-compartment tanks and multiple drawing devices are well known in the automotive field.

 More and more often, in fact, the fuel tanks of motor vehicles are located under the base of the vehicles and then have complex shapes to adapt to the different constraints of mechanical layout. For example, it is sometimes necessary to have elements such as an exhaust line or the drive shaft under the fuel tank. Therefore, the tank has several compartments separated by partitions including a main compartment and at least one auxiliary compartment, and the associated drawing device must allow the best use of the fuel present in each compartment of the tank.

 To do this, a drawing device is already known which comprises an electric fuel pump, called a transfer pump, capable of sucking the fuel present in the auxiliary compartments of the tank to bring it into the main compartment where the pump is placed. fuel supply to the vehicle engine.

 This type of drawing device is however complex, expensive and consumes electrical energy.

Document FR-2 667 583 is known, belonging to
Applicants, a drawing device which allows all the compartments to be emptied simultaneously. This device comprises a pipe which passes through the lower part of each compartment of the tank and which terminates in the supply pump located in the main compartment thereof. This pipe comprises in each compartment a drawing system provided with a valve. Each valve consists of a float held by a cage. Each float rises when the liquid is present in sufficient quantity in each compartment and lowers, closing the passage, when there is no longer any liquid in the corresponding compartment.

 Furthermore, document JP-A-6 283 222 describes a device for drawing fuel from a tank with two compartments, which comprises in the auxiliary compartment a suction pipe provided with a valve. This suction line is connected to the main line located at the bottom of the main compartment. The main line is itself connected to the pump located in the main compartment.

 The two abovementioned drawing devices are complex and require the use of valves in all the compartments to prevent the entry of air into the pipes when these compartments are empty.

 Finally, from document US Pat. No. 3,981,321, a multiple drawing device is known which allows fuel to be drawn simultaneously from two separate tanks. This device comprises suction lines and return lines associated with the various tanks. The suction lines are connected to a suction pump and to distribution means in order to simultaneously aspirate the fuel present in the two tanks. The return lines are connected to a pressure regulator system connected to the pump. Thus, when the fuel level in one tank is lower than the fuel level in the other tank, a pressure difference is created between the corresponding tank and the connections of the various lines. The pressure difference between the different suction lines leads to a greater influx of fuel from the most filled tank to supply the pump so that the fuel in the two tanks is again at the same level. In addition, the pressure difference between the return lines causes a greater influx of fuel back into the less filled tank in order to bring the latter to the same level as that of the most filled tank.

 This drawing device is complex and requires a valve system which makes it possible to regulate the supply of the pump and to close, if necessary, the empty tanks.

 In order to overcome the drawbacks of the prior art, the invention proposes a new light multiple drawing device, of simple and economical design and which makes it possible to suck a fluid simultaneously in several compartments of the same tank while favoring a particular compartment. , so that it is emptied last and there is always enough fluid in this privileged compartment to maintain a sufficient seal at the outlet of the associated suction pipe.

 More specifically, the device for multiple drawing of liquid from a reservoir comprises several compartments including a main compartment and at least one auxiliary compartment, said device comprising in each compartment a circuit for sucking and returning the liquid contained in the compartment, comprising a suction line and a return line intended to convey the unconsumed liquid to each compartment, the suction lines being arranged to suck the liquid simultaneously in all the compartments. I1 is characterized in that the arrangement of the suction and return circuits is provided so that the liquid suction and return regime in each auxiliary compartment and in the main compartment is such that the latter is emptied last and in that there is a valve on each suction line of each auxiliary compartment, capable of opening when the liquid level is above a limit value and of closing when the liquid level present in said compartment auxiliary is less than this value.

 According to a particularly advantageous embodiment of the device according to the invention, means are provided for limiting the flow of return liquid in each auxiliary compartment, so that said flow is less than that conveyed in the main compartment.

 According to another characteristic of the invention, the arrangement of the return circuit in each auxiliary compartment is provided such that the liquid return flow is sufficient to maintain a minimum liquid level in each auxiliary compartment in order to ensure a good seal between each valve and each suction line.

 According to a particular embodiment of the device according to the invention, the suction circuits are capable of sucking the same quantity of liquid in all the compartments of the tank.

 The description which follows with reference to the appended drawings given by way of nonlimiting examples will allow a better understanding of the invention and how it is carried out.

 - Figure 1 is a schematic sectional view of a tank with two compartments comprising a drawing device according to the invention.

 - Figure 2 is a schematic detail view of the valve provided on the suction line of an auxiliary compartment of the device of Figure 1 when the liquid level in said compartment is horizontal.

 - Figure 3 is a schematic detail view of the valve of Figure 1 when the liquid level in the auxiliary compartment has different inclinations.

 In Figure 1, there is shown a motor vehicle tank 1, which has two compartments including a main compartment 2 and an auxiliary compartment 3. These main 2 and auxiliary 3 compartments are separated in the lower part of the tank 1 by a vertical partition 4 formed in the bottom of it. In addition, in FIG. 1, there is a device for multiple drawing of liquid composed of two suction and return circuits 5, 9, associated respectively with the two compartments 2, 3.

 The suction and return circuit 5, associated with the main compartment 2, comprises a liquid suction line 6 and a liquid return line 8 arranged vertically in parallel in said compartment 2. The suction line 6 comprises at its lower end, a suction mouth located near the bottom of the tank 1. In addition, the suction line 6 has an upper end which opens to the outside of the tank 1 via a junction piece 19 on a first connection line 20 connected to a pump not shown here. In addition, there is provided a filter 7 arranged on the suction mouth of said suction pipe 6, capable of retaining any impurities present in the liquid at the bottom of the tank 1. Furthermore, the return pipe 8 plunges in the main compartment 2 from a second connection line 23, in order to convey to the bottom of the compartment the liquid not consumed, here the fuel not consumed by the engine. A junction piece 22 is also provided for connecting the return pipe 8 with the second horizontal connection pipe 23.

 The suction and return circuit 9 disposed in the auxiliary compartment 3 also includes a suction line 10 and a liquid return line 17. The suction line 10 of the second suction and return circuit has, in lower part located near the bottom of compartment 3, a bend 1 1 to 180O, so that the lower suction end 12 of said suction pipe 10 is directed towards the top of the auxiliary compartment 3. The pipe d the suction 10 is connected here outside the tank 1 to an intermediate pipe 18 also connected by the connecting piece 19 to the connection pipe 20.

 It can be seen in FIG. 1 that the suction pipe 10 of the second suction and return circuit 9 is provided, on the one hand with a valve which makes it possible to close this suction pipe 10 when the quantity of liquid present in the auxiliary compartment 3 is no longer sufficient and, on the other hand, a filter 16 making it possible to retain the impurities present in the liquid at the bottom of said compartment 3.

 With particular reference to FIGS. 1 and 2, the valve mounted on the suction pipe 10 comprises a float 13 disposed above the lower end 12 of the suction pipe 10. The float 13 has a density less than that of the liquid contained in the reservoir 1. In addition, the float 13 has a lower part 14 forming a plug and intended to cooperate with a receiving seat 15 formed in the suction line 10 at its lower end 12. According to the mode of embodiment shown, the float 13 is a cylinder of diameter d and the plug 14 has a substantially conical shape, tip pointing downwards. The float 13 is guided in translation above the lower end 12 of the suction pipe 10 by a cage not shown here.

 With reference to FIG. 2, the operation of the float valve 13 will be briefly described.

When the liquid level in the auxiliary compartment is greater than or equal to a limit level which will be specified later, the float rises under the pressure of the liquid which is then sucked in by the suction pipe 10. An experimental calculation makes it possible to determine with respect to a reference level ho where the lower end 12 of the pipe 10 is situated, the height of liquid AH above which the quantity of liquid is sufficient to lift the float 13 from the seat 15. If we designate by SIF the mass of the float, by d the diameter of the cylindrical float and by Pc the density of the liquid, we then have:
4MF
AH = # d # c
The limit liquid level is then equal to AH + ho. As can be seen in Figure 2, the liquid level in the compartment is here equal to AH + ho + h and the float 13 is then at a height h above the end 12 of the pipe 10 and is immersed of the height AH in the fuel.

When the liquid level is below the limit value equal to
AH + ho, the float 13, under the effect of its own weight rests on the lower end 12 of the suction pipe 10. The plug 14 bears against the walls of the seat 15 and seals the pipe tightly 10. The seal can be reinforced, if necessary, by interposing between the seat 15 and the plug 14, a seal here not shown.

 Furthermore, it can be seen in FIG. 1 that the liquid return pipe 17 of the second suction and return circuit 9 is connected outside the tank to an intermediate pipe 21 connected to the second connection pipe 23 by l 'intermediate of the connecting piece 22. The intermediate pipe 21 includes a flow limiter 24, here a throttle disposed inside said pipe 21, so as will be explained in more detail later, to limit the flow of liquid return to the auxiliary compartment 3 relative to the flow of liquid back to the main compartment 2. The main compartment 2 of the tank 1 is thus favored relative to the auxiliary compartment 3 so that the main compartment 2 is emptied last.

 According to the embodiment shown in Figure 1, the suction lines 6, 10, return 8, 17, are identical. Similarly, the intermediate lines 18, 21 and connection 20, 23 have here the same diameter equal to that of said suction and return lines.

 We will now describe in more detail the overall operation of the multiple drawing device of FIG. 1.

 When the tank 1 is filled with fuel, the latter is sucked through the pump not shown in the suction lines 6, 10 to the motor not shown, via the connection line 20. The suction lines 6 , 10 suck up substantially the same quantity of liquid simultaneously in the main 2 and auxiliary compartments 3. Q2a denotes the flow of fuel sucked into the suction line 6 and Q3a denotes the flow of fuel sucked into the suction line 10. The flow Q2a is here substantially equal to the flow a The fuel level in the auxiliary compartment 3 being greater than the aforementioned limit value, the float 13 of the valve is raised, which allows the fuel to be sucked into the suction line 10, via the open lower end 12. It should be noted that the total quantity of fuel sucked in, noted Qa is equal to Q2a + Q3a. This quantity Qa is not completely consumed by the engine and there is a quantity of fuel returning to the tank 1. This quantity of return fuel is conveyed to the main 2 and auxiliary 3 compartments respectively by the return lines 8, 17, via the connection line 23. It should be specified that the fuel returning to the auxiliary compartment 3 flows in the intermediate line 21 then in the return line 17 to arrive therein. The return fuel flow in the main compartment is noted Q2r and that in the auxiliary compartment is noted Q3r. The total return flow Qp is noted. We then have Qr = Q2r + Q3r, the flow Qr returning in the connection pipe 23 and being divided into flows Q2r and Q3r from junction 22 and towards compartments 2, 3 of the tank 1.

 In addition, the flow limiter 24 arranged in the intermediate pipe 21 creates a significant pressure drop in the return pipe 10 to the auxiliary compartment 3, so that the flow Q3r is much lower than the flow Q2r.

We note x% the percentage of the flow Qr returning to the auxiliary compartment 3 of the tank 1. We then have: x
Q3r = ~~ - Qr
100 x
Q2r = 1- Qr
100
In the case where the flow limiter 24 closes off the intermediate pipe 21, there is then x = 0, that is to say that the whole of the return flow Qr is conveyed in the main compartment 2. At the end of while the engine is running, the two compartments will empty.

 However, the main compartment 2 receiving the fuel flow back from the engine Q2r = Qr will empty more slowly than the auxiliary compartment 3 of the tank 1.

 Thus, after a certain time the fuel level in the auxiliary compartment 3 of the tank 1 will be lower than the limit level equal to AH + ho and the float 13 will then rest on the seat 15 of the end 12 of the pipe suction 10 in order to close said pipe.

The fuel will then no longer be sucked through the suction line 10 and the suction flow Q3a will become zero, we will then have as suction flow a = Qa This state will last until the main compartment 2 of the tank 1 is almost empty and the system will therefore have made it possible to use almost all of the fuel present in tank 1.

 It should be noted that if we consider that the fuel level in the tank 1 is horizontal, without vibration or acceleration of the vehicle, the amount of fuel in the auxiliary compartment 3 that can be sucked up, then corresponds to a fuel height equal to AH + ho. Thus, it may be advantageous to give a form of reservoir making it possible to minimize the liquid at the bottom of the compartments and, therefore, to minimize the volume of fuel which cannot be sucked in and corresponding to the height AH + ho.

 However, it should be noted that several phenomena can disturb the above-mentioned theoretical operation.

 In fact, during driving, the various movements and accelerations of the vehicle can modify the inclination of the fuel level present in the auxiliary compartment 3 relative to the inclination of the bottom of said compartment.

 For example, as can best be seen in FIG. 3, for the same volume of fuel in the auxiliary compartment 3 of the tank 1, the fuel level can for example tilt according to the levels 25a, 25b or 25c. The liquid height in line with the float 13 and the end 12 of the suction line 10 is then referenced ha, hb and hc respectively. The height ha here corresponds to the closing dimension of the valve and we then have ha = ho + AH.

 As shown in Figure 3, if the vehicle brakes, the fuel level in the tank will tilt according to level 25b and the height of liquid in line with the float is then equal to hb greater than the height ha . Thus, the float will lift and the fuel will then be sucked through the suction line 10. In addition, in the event of acceleration of the vehicle, the fuel level will tilt according to the level 25c and the slope to the right of the float 13 of the end 12 of the suction line 10 can be lowered to a value equal to hc less than the height of liquid ha. In this case, the float will land on the seat 15 of the end 12 and the suction line will then be closed.

 In all the operating cases described above where x = 0, it is assumed that the sealing of the plug 14 of the float 13 on the seat 15 is perfect from the moment when the float 13 rests on the end 12 of the pipe. suction 10 disposed in the auxiliary compartment 3.

 When the seal between the plug 14 and the seat 15 is not perfect, there may then be air suction in the suction line 10 thus producing a supply fault in the vehicle engine. In fact, during the life of the vehicle, the seal between the plug 14 and the seat 15 may deteriorate. It is also possible that dust or particles present at the bottom of the tank are interposed between the cap and the seat.

 To overcome this drawback, it is advantageous that a small part x% of the amount of fuel Or in return circulating in the connection line 23 is conveyed in the direction of the auxiliary compartment 3. The flow rate Q3r being different from zero then serves to compensate the drop in the fuel level in said auxiliary compartment 3 when it is below the limit value AH + ho in order to maintain a minimum liquid level sufficient to ensure a good seal between the float 13 and the seat 15 of the pipe suction 10.

On the other hand, when the seal between the plug 14 and the seat 15 is perfect and there is no tilting effect of the fuel level in the auxiliary compartment 3 as shown in FIG. 3 , the flow Q3r will tend to increase the height of the liquid in said compartment 3. Thus, the float will therefore, from a certain level higher than the aforementioned limit level, release the end 12 of the suction line 10. The fuel will be sucked through the suction line 10 until the float 13 rests on the end 12. The float 13 will therefore oscillate permanently around an equilibrium state corresponding to a height of liquid in the auxiliary compartment 3 of tank 1 equal to AH + ho.

 The percentage x of the return flow Or conveyed to the auxiliary compartment 3 of the tank 1 is as low as possible. In the case of a diesel engine, an experimental value of the percentage x has been determined of between approximately 2% and 5%.

 The present invention is in no way limited to the embodiment described and shown, but a person skilled in the art can make any variant which conforms to his spirit.

We can for example consider that the suction lines 6, 10 are different so that the flow rates of aspirated liquid Q2a and q3 are different, Q3a being greater than a
It is also conceivable that a fuel trap is placed around the end 12.

Claims (10)

 1. Device for multiple drawing of liquid from a tank (1) comprising several compartments (2, 3) including a main compartment (2) and at least one auxiliary compartment (3), said device comprising in each compartment (2, 3) a suction and return circuit (5, 9) of the liquid contained in the compartment, comprising a suction line (6, 10) and a return line (8, 17) intended to convey to each compartment (2, 3) the non-consumed liquid, the suction lines being arranged to suck the liquid simultaneously in all the compartments (2, 3), characterized in that the arrangement of the suction and return circuits (5, 9) is designed so that the liquid suction and return regime in each auxiliary compartment (3) and in the main compartment (2) is such that the latter is emptied last and in that there is a valve on each suction line (10) of each auxiliary compartment (3), ap te to open when the liquid level is above a limit value and to close when the liquid level present in said auxiliary compartment (3) is lower than this value.  2. Multiple drawing device according to claim 1, characterized in that there is provided a means (24) for limiting the flow of return liquid in each auxiliary compartment, so that said flow is lower than that conveyed in the main compartment (2).  3. Device according to one of claims 1 or 2, characterized in that the arrangement of the return circuit (17) in each auxiliary compartment (3) is provided so that the liquid return flow is sufficient to maintain a minimum level of liquid in each auxiliary compartment to ensure a good seal between each valve (13, 14, 15) and each suction line (10).  4. Device according to any one of claims 1 to 3, characterized in that the suction circuits (6, 10) are capable of sucking the same amount of liquid in all the compartments (2, 3) of the tank (1 ).  5. Device according to any one of claims 1 to 4, characterized in that the percentage x of the total flow of liquid back into each auxiliary compartment is between approximately 2% and 5%.  6. Device according to any one of claims 1 to 5, characterized in that each valve comprises  - a float (13) provided with a plug (14),  - A seat (15) allowing the passage of the liquid and on which the  cap (14) can be applied tightly,  - a cage to limit the movements of the float (13).  7. Device according to any one of claims 1 to 6, characterized in that it comprises  - a first connection pipe (20) provided with a part  junction (19) to which the pipes are connected  suction (6, 10), and  - a second connection pipe (23) provided with a part  junction (22) to which the supply lines are connected  back (8, 17).  8. Device according to claim 7, characterized in that it comprises on the one hand a first intermediate pipe (18) interposed between the junction piece (19) of the first connection pipe (20) and each suction pipe (10) associated with each auxiliary compartment (3), and on the other hand a second intermediate pipe (21) between the junction piece (22) of the second connection pipe (23) and each associated return pipe (17) to each auxiliary compartment (3).  9. Device according to claim 8, characterized in that the means for limiting the return flow in each auxiliary compartment (3) is a throttle (24) disposed inside the second intermediate pipe (21).  10. Tanks with several compartments comprising a multiple drawing device according to any one of claims 1 to 9.